The MyC64 core is my go at writing a FPGA based C64 emulator. It is a project I started during the summer of 2020, at that point targeting the ULX3S board. Initially it made good progress but then nothing happened for a long long time.
Years later the Analogue Pocket came along with its openFPGA framework and slightly after Christmas 2023 I decided to get started on its current incarnation.
Have a look at this Youtube playlist (that I will try to keep up-to-date when something noteworthy is added).
In short though, the core is still work-in-progress but quite a lot of things actually do work (plus minus some emulation discrepancies).
Simply unzip the MyC64-Pocket.zip (from releases) in the root directory of
the Analogue Pocket's SD card.
For legal reasons all ROMs are kept outside the FPGA bitstream distributed here. The Commodore ROMs (three for the C64 and two for the 1541) can be fetched with
wget http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/c64/basic.901226-01.bin
wget http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/c64/characters.901225-01.bin
wget http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/c64/kernal.901227-03.bin
wget http://www.zimmers.net/anonftp/pub/cbm/firmware/drives/new/1541/1540-c000.325302-01.bin
wget http://www.zimmers.net/anonftp/pub/cbm/firmware/drives/new/1541/1541-e000.901229-01.binthey then need to be placed in /media/Assets/c64/common/ as follows
/media/Assets/c64/common/basic.bin
/media/Assets/c64/common/characters.bin
/media/Assets/c64/common/kernal.bin
/media/Assets/c64/common/1540-c000.bin
/media/Assets/c64/common/1541-e000.binAll assets are to be placed in /media/Assets/c64/common/ or sub-directories
thereof.
Standard .prg files are supported.
Select the desired .prg file from the Core Settings->Load & Start PRG and
the following sequence will be initiated
.prg into RAMRUN<RET> key sequenceSuggestions are Supermon+64 and the High Voltage SID Collection (HVSC) converted to PSID64 format.
For games it is recommended to get hold of the OneLoad64 collection of 2100+
titles OneLoad64-Games-Collection-v5.7z (just google it). From what I can
tell the majority of the collection's crunched .prg files (found in
AlternativeFormats/PRGs/Crunched/) load up properly. It is important to pick
the crunched ones as the uncrunched will attempt to replace the entire RAM
which is not supported while the system is running.
The Pocket appears to truncate directories containing more than 1500 files so indexing as below is suggested.
$ p7zip -d OneLoad64-Games-Collection-v5.7z
$ cd AlternativeFormats/PRGs/Crunched/
$ for letter in {a..z}; do mkdir ${letter^}; mv ${letter}*.prg ${letter^}/; mv ${letter^}*.prg ${letter^}/; done
$ for digit in {0..9}; do mkdir ${digit}; mv ${digit}*.prg ${digit}/; doneOf course as the core is in development not every .prg will function
correctly. So to avoid frustration and help new users out we have the following
wiki page Working
PRGs that anyone
(on github) can edit. Please feel free to update it with your findings!
Currently the following cartridge formats are supported
.crt
format specification.
This is the main format used by the .crt files in the OneLoad64 games
collection. The cartridge is limited to 128KB of storage.Select the desired .crt file from the Core Settings->Load & Start CRT
browser. The emulated cartridge will be inserted into the system and the C64 is
automatically reset to boot up its contents.
Cartridges of unsupported formats are silently ignored (and no reset is triggered).
The core contains emulation of a Commodore 1541 floppy disk drive (currently read-only). Emulation is low level and the real ROMs are used. As a result the decode circuitry need to have the raw GCR bitstream (that the read head of a real drive would see) as its input.
In other words the common .d64
format is not directly
supported but rather the lower level .g64
format must be used.
A bit further down the road the housekeeping CPU could probably perform this
conversion on the fly but right now .d64 files need to be converted to .g64
format manually.
The utility program nibconv from
NIBTools can be used to
convert between .d64 and .g64.
Usage example:
$ nibconv somedisk.d64 somedisk.g64You can download pre-build binaries for windows from c64preservation.com files.
For Linux it is obtained and built as follows
$ git clone --recurse-submodules https://github.com/OpenCBM/OpenCBM.git
$ cd OpenCBM
$ make -f LINUX/MakefileOn MacOSX you can auto-build nibtools using Homebrew and hitorisensei/homebrew-taps/nibtools tap
$ brew install hitorisensei/homebrew-taps/nibtoolsSelect the desired .g64 file from the Core Settings->Load G64 Slot
browser and the disk image will be inserted into the emulated 1541 floppy
drive.
At this point the user needs to do normal interaction such as LOAD"$",8
followed by a LIST to get a directory listing or simply a LOAD"*",8
followed by a RUN to load and run the first program of the disk.
Note that on the C64 keyboard " is <SHIFT>+2 and $ is <SHIFT>+4 (read
the section about sticky keys for how to access the shift modifier on the
virtual keyboard).
The gamepad is mapped to the C64 joystick port as follows
Pressing left-of-analogue brings up (toggles) the on-screen-display containing a virtual keyboard and a small menu system for settings.
For the virtual keyboard the face-x button toggles sticky keys (useful for modifiers such as shift) and the face-y button clears any sticky key. Normal key press is accomplished with the face-a button.
Pressing trig-l1 and trig-r1 navigates through the different menu tabs.
Controllers can be mapped to C64 joystick ports in the MISC menu tab and there you will also find a reset button for the emulator core.
A physical keyboard is supported while docked. The keyboard is expected to show
up on the third input (i.e. cont3_joy). For details on the key mapping see
table hid2c64 in source file src/bios/main.c.